In modern music performance/recording, mechanical vibration effects on recorded/reproduced audio frequency program material are responsible for perceived (and measured) degradation of the natural transient response of all audio signals captured, stored, replayed, or reproduced by equipment of the prior art. It is a problem that exists at the system level, in all components of the system in one form or another.
The audio industry, since the inception of digital audio in the early 1980s, has faced criticism that digital recordings did not sound as good as their analog counterparts. Indeed, some fine quality recordings were produced by the technology of the late 1950's with analog recording and playback means. This was partially due to the prevalent design techniques used for microphones and microphone stands, along with the materials used in the wiring, and the design of enclosures and chassis. It was also partially due to a more direct signal recording and playback equipment path. That is, there were fewer pieces of equipment to contribute bad effects to the program material, and extra “processing” was not thought of as necessary. Additionally, since the effects of vibration, in some respects, are more detrimental to digital recording and reproduction than to analog processing, the analog recording/playback systems sounded better. In fact, they did indeed capture a better transient response in program material than did the newer digital recordings for reasons disclosed herein.
Microphones are the most susceptible link in the reproduction chain due to their proximity to the original sound source and their natural susceptibility to vibrations. They are self-evidently and inherently, the most sensitive component due to their function, which is to convert airborne vibrations sensed by the element(s) into low level electrical signals for further amplification, storage, analysis, or later reproduction. However, microphone designers have not successfully understood the issue of microphone enclosure vibrations that are also received from the environment, and how they translate into extra modulations which add to the sound already received and are converted by the main microphone sensing element(s). These enclosure-borne vibrations seriously degrade the signal received by the microphone sensing element(s). More specifically, it has been determined that the resonances of various materials comprising the microphone mounting mechanism(s) and stand assembly can cause smeared signal transients.
Common sources of vibration (unwanted inputs to the system) include the program material of interest, “monitoring” equipment used to listen to the desired program material during the recording/reproduction process, internal vibrations generated by power transformers or the mechanisms used to manipulate media (CD or tape transports) used to record or process the desired program material. Even air pressure changes caused by low frequency air handler equipment for HVAC systems (Heating, Ventilation, and Air-Conditioning) can cause vibrations to be introduced into the recorded/amplified program.
The degradation comes in multiple forms, depending on: (a) the type of equipment (analog or digital based signal processing), (b) location in the recording/reproduction chain (microphone or front end processing vs compact disc player playback and power amplifier combination back end processing), and (c) the relative magnitude of the vibration in relation to the signal processing being performed at that stage in the chain. Common effects of the various vibration sources include, but are not necessarily limited to: (a) data clock perturbations in digital systems as a byproduct of the reference crystal vibration (jitter, drift, modulation based on program material), (b) microphonic transfer of vibration to power supply lines which then subsequently modulate the desired program material as a product of amplification, and (c) microphonic transfer of vibration to the microphone electronics through the microphone stand/holder assembly and microphone wiring which then subsequently modulates the desired program material as a by-product of sensing and amplification.
Referring initially to FIG. 1, illustrated is a conventional microphone stand 100 holding a conventional microphone 110. The conventional microphone stand 100 comprises a base 120, a first vertical support pole 121, a second vertical support pole 122, an adjustable support pole 123, a first support pole clutch assembly 124, a second support pole clutch assembly 125, a pole-to-microphone adapter 130, a microphone holder 140, and cable clamps 150. The microphone stand 100 stands upon a floor 101 and supports the microphone 110. The microphone 110 has a microphone body 111 coupled to a microphone cable 160. The microphone cable 160 is coupled to the first vertical support pole 121, the second vertical support pole 122, and the adjustable support pole 123 with the cable clamps 150. In the embodiment shown, the base 120, the first vertical support pole 121, second vertical support pole 122, adjustable support pole 123, first support pole clutch assembly 124, second support pole clutch assembly 125, pole-to-microphone adapter 130, microphone holder 140, and cable clamps 150 typically comprise resonant materials such as metal, hard plastic, etc. In one embodiment, the base 120 may have rubber feet 126 to decouple vibration arising from the floor 101.
The major effect of the various vibration sources is the microphonic transfer of vibration to the microphone electronics through the microphone stand/holder assembly and microphone wiring. The vibrations subsequently modulate the desired program material as a by-product of sensing and amplification. In most cases little special care has been taken to isolate the microphone sensing element(s) (not shown) from the microphone body 111. In an embodiment considered to be among the best of the prior art, the microphone holder 140 comprises some form of elastic suspension bands 141 coupled between a circumferential ring 142 and the microphone 110. Various forms of this general method of isolation are disclosed in U.S. Pat. No. 6,459,802 to Young, U.S. Pat. No. 4,546,950 to Cech, U.S. Pat. No. 4,396,807 to Brewer, U.S. Pat. No. 4,194,096 to Ramsey, ostensibly to isolate the microphone 110 from floor-borne, low frequency vibrations. The above listed patents are hereby incorporated by reference. While it is desirable to isolate the microphone/stand combination from floor-borne vibrations, the methods of the prior art subject the microphone elements to significantly larger degradations from airborne vibrations through the microphone enclosure (the microphone body 111 or case) which is generally not protected in any way from airborne vibrations. Extraneous vibrations can be additionally magnified when the microphone (sensor) is suspended via these weblike mechanisms, as in the listed prior art, in an effort to isolate it from the low frequency vibrations transmitted from the floor. This is accomplished at the expense of exposure to the significantly higher levels and wider frequency spectrum of vibration levels available directly through the air. These vibrations must also be addressed in the quest to control the recording/reproduction process in an effort to preserve the transient response of the desired signal to be recorded or processed. With the prior art, the conventional microphone 110 receives, and inadvertently converts to an electrical signal, those vibrations it receives through the microphone body 111 and the microphone cable 160, along with the airborne vibrations sensed by the microphone element from the desired signal. Vibrations in the microphone stand/holder assembly also can cause very small movements of the entire microphone 110, and therefore the element(s) of the microphone while it is receiving the desired signal. Vibrations of the microphone stand 100 also cause a lever arm effect on the suspended microphone 110 which magnifies the effect of small vibrations in the microphone stand 100.
In most cases little special care has been taken to isolate the microphone sensing element(s) from the microphone body. Generally, the microphone itself is, in the presumed best form of the prior art, suspended in air via elastic webs, ostensibly to isolate it from floor-borne low frequency vibrations. While it is desirable to isolate the microphone/stand combination from floor-borne vibrations, the method of the prior art subjects the microphone assembly to significantly larger degradations from airborne vibrations through its enclosure (the microphone body or case) which is not protected in any way from extraneous airborne vibrations. Ideally, the best mounting mechanism would reveal the main (desired) sensing element(s) to the sounds to be converted into electrical signals, while keeping the body of the microphone, and therefore the remaining electronics inside it, isolated from extraneous airborne vibrations. With the prior art, the microphone receives and inadvertently converts vibrations it receives through its case and the microphone wire, along with the vibrations sensed by the main (desired) element from the desired signal. Consequently, any vibrations, including extraneous solid-body vibrations, received through the microphone body ill or its holding mechanism 140, stand 100, and cabling 160 get combined with the desirable sounds from an intended source impinging on the main microphone element (s); thereby the net combination of these signals becomes the overall signal produced by the microphone 110, microphone holding system 100, and cabling 160.
Accordingly, what is needed in the art is a microphone support system that does not suffer from the transmission of extraneous vibrations to the sensing element(s) of the microphone.